Fun run and Foot race

Fun run noun - A footrace run for fun (often including runners who are sponsored for a charity).

Foot race and fun run are semantically related. In some cases you can use "Foot race" instead a noun phrase "Fun run".

Foot race noun - A race run on foot.

Fun run and foot race are semantically related. Sometimes you can replace phrase "Fun run" with "Foot race", this phrases are similar.